This invention relates generally to catheters, and particularly to intravascular catheters for use in percutaneous transluminal coronary angioplasty (PTCA), or the delivery of stents.
In a typical PTCA procedure, a dilatation balloon catheter is advanced over a guidewire to a desired location within the patient's coronary anatomy to position the balloon of the dilatation catheter along the stenosis to be dilated. The balloon is then inflated one or more times with fluid at relatively high pressures (generally 4–16 atmospheres) to dilate the stenosed region of the diseased artery. A stent is commonly implanted within the artery, typically by delivery to the desired location within the artery in a contracted condition on a balloon of a catheter which is similar in many respects to a balloon angioplasty catheter. Inflation of the balloon expands the stent, thereby implanting it in the artery. Following the dilatation or stent expansion, the balloon is deflated and the catheter repositioned or withdrawn from the artery.
In rapid exchange type balloon catheters, the catheter has an inflation lumen extending from the proximal end of the catheter to a balloon on a distal shaft section, a distal guidewire port at the distal end of the catheter, a proximal guidewire port located distal to the proximal end of the catheter, and a relatively short guidewire lumen extending therebetween. The rapid exchange junction located at the proximal guidewire port should provide a good transition in flexibility from the relatively stiff proximal shaft section to the relatively flexible distal shaft section. One difficulty has been forming a junction which is flexible, yet kink resistant and rugged.
To help meet the desire for a catheter having sufficient pushability and crossability, while maintaining trackability within the patient's tortuous vasculature, prior art designs have supplemented polymer catheter shafts with a support mandrel. Other prior art designs have addressed these handling and performance issues by using materials of different stiffness for the proximal and distal portions of the catheter, and employing a high strength metallic proximal shaft section, commonly called a hypotube. To prevent kinking at the junction of these two materials, while maintaining trackability, some conventional designs have employed reinforcing layers or stiffening wires to bridge the transition in catheter shaft material. Despite these attempts, prior art designs have suffered from various drawbacks relating to these handling and performance issues.
Accordingly, it would be a significant advance to provide a catheter having an improved catheter shaft junction between shaft sections such as the proximal and distal shaft sections. This invention satisfies these and other needs.